Discrimination of first- and second-order regular intervals from random intervals as a function of high-pass filter cutoff frequency

This study extends the work of Kaernbach and Demany [J. Acoust. Soc. Am. 104, 2998–2306 (1998)] in which regular interval stimuli (RIS) click trains with first-order intervals could be discriminated from random-interval click trains, but RIS with second-order intervals could not. Kaernbach and Demany concluded that their results cast doubt on autocorrelation as a method of analysis for such stimuli. The present study investigated the same stimuli, but for a variety of filter conditions. The results suggest that while RIS click trains with first-order intervals are more easily discriminated from random-interval stimuli than second-order interval RIS click trains, discrimination based on second-order intervals is possible except when the stimuli are high-pass filtered above 8 kHz, i.e., above the spectral region of phase locking.